A grim reaper knocking on a door labelled "open source"

What About The Droid Attack On The Repos?

You might not have noticed, but we here at Hackaday are pretty big fans of Open Source — software, hardware, you name it. We’ve also spilled our fair share of electronic ink on things people are doing with AI. So naturally when [Jeff Greerling] declares on his blog (and in a video embedded below) that AI is destroying open source, well, we had to take a look.

[Jeff]’s article highlights a problem he and many others who manage open source projects have noticed: they’re getting flooded with agenetic slop pull requests (PRs). It’s now to the point that GitHub will let you turn off PRs completely, at which point you’ve given up a key piece of the ‘hub’s functionality. That ability to share openly with everyone seemed like a big source of strength for open source projects, but [Jeff] here is joining his voice with others like [Daniel Stenberg] of curl fame, who has dropped bug bounties over a flood of spurious AI-generated PRs.

It’s a problem for maintainers, to be sure, but it’s as much a human problem as an AI one. After all, someone set up that AI agent and pointed at your PRs. While changing the incentive structure– like removing bug bounties– might discourage such actions, [Jeff] has no bounties and the same problem. Ultimately it may be necessary for open source projects to become a little less open, only allowing invited collaborators to submit PRs, which is also now an option on GitHub.

Combine invitation-only access with a strong policy against agenetic AI and LLM code, and you can still run a quality project. The cost of such actions is that the random user with no connection to the project can no longer find and squash bugs. As unlikely as that sounds, it happens! Rather, it did. If the random user is just going to throw their AI agent at the problem, it’s not doing anybody any good.

First they came for our RAM, now they’re here for our repos. If it wasn’t for getting distracted by the cute cat pictures we might just start to think vibe coding could kill open source. Extra bugs was bad enough, but now we can’t even trust the PRs to help us squash them!

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Recreating Mega Man’s Mega Buster

Mega Man is a popular video game character who is perhaps most notable for having a sort of lasery-type blaster for an arm. A real hand cannon, if you will. It’s officially called the Mega Buster, and [Arnov Sharma] recently recreated it for cosplay purposes.

Key to any good cosplay build is getting the visuals right, and [Arnov] achieved that well. The Mega Buster was first recreated in Fusion 360, scaled to an appropriate size to fit [Arnov]’s arm. It was 3D printed in several sections, with the body including a grab handle and fire button inside, and the side panel and blaster nozzle having provision for installing LEDs. The former is the blaster’s “power meter” which shows how many shots it has left until it runs out of energy, with the blaster able to fire six times before needing to cooldown. A Raspberry Pi Pico controls the LEDs and provides sound effects with the aid of a PAM8403 class D amplifier module and a small speaker.

The 3D files are available on Instructables for the curious. Perhaps by virtue of its arm-mounted nature, this build reminds us of the venerable Pip Boy from Fallout, of which we’ve seen many grand recreations before. Video after the break.

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Inside A Compact Intel 3000 W Water-Cooled Power Supply

Recently [ElecrArc240] got his paws on an Intel-branded 3 kW power supply that apparently had been designed as a reference PSU for servers. At 3 kW in such a compact package air cooling would be rather challenging, so it has a big water block sandwiched between the two beefy PCBs. In the full teardown and analysis video of the PSU we can see the many design decisions made to optimize efficiency and minimize losses to hit its 80 Plus Platinum rating.

For the power input you’d obviously need to provide it with 240 VAC at sufficient amps, which get converted into 12 VDC at a maximum of 250 A. This also highlights why 48 VDC is becoming more common in server applications, as the same amount of power would take only 62.5 A at that higher voltage.

The reverse-engineered schematic shows it using an interleaved totem-pole PFC design with 600 V-rated TI LMG3422 600V GaN FETs in the power stages. After the PFC section we find a phase-shifted full bridge rectifier with OnSemi’s SiC UF3C065030K4S Power N-Channel JFETs.

There were a few oddities in the design, such as the Kelvin source of the SiC JFET being tied into the source, which renders that feature useless. Sadly the performance of the PSU was not characterized before it was torn apart which might have provided some clues here.

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Exclamation Point Indicates Worthy Notifications

As far as punctuation goes, the exclamation mark is perhaps the most eye-catching of the bunch. That’s why [Conrad Farnsworth] thought this form would be perfect for his Home Assistant notifier build. 

The key to this build is the large bi-color printed housing in the shape of an exclamation mark. It makes for an attractive wall-hanging, but it also perfectly serves the purpose [Conrad] had in mind. Inside the enclosure is an ESP32, hooked up to a string of 16×8 LED matrixes which are commanded over I2C. These sit behind a white panel in the enclosure to nicely diffuse the light and make their output more readable. The ESP32 displays notifications on the LEDs that are fed from Home Assistant, such as when the mailbox sensor is triggered or if a vehicle is detected in the driveway. There’s also a bell on the unit to provide audible notifications, which us dinged with a solenoid fired via a 2N2222 transistor switching a 12-volt supply from a boost converter.

It’s a neat build that fits nicely into [Conrad]’s daily life and appears to have some genuine utility. If you’re looking for other ways to neatly display notifications where you can see them, you might consider whipping yourself up a smart mirror. Video after the break.

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Why Chains Are Still Better For Bicycles Than Belts

Theoretically a belt drive makes for a great upgrade to a bicycle, as it replaces the heavier, noisy and relatively maintenance-heavy roller chain with a zero-maintenance, whisper-quiet and extremely reliable belt that’s rated at an amazing 20-30,000 km before needing a replacement. Of course, that’s the glossy marketing brochure version of reality, which differed significantly from what [Tristan Ridley] experienced whilst cycling around the globe.

Although initially he was rather happy with his bike, its sealed car-like Pinion gearbox and Gates carbon belt drive system, while out in the wilds of Utah he had a breakdown when the belt snapped. When the spare belt that he had carried with him for the past months also snapped minutes later after fitting it on, it made him decide to switch back to the traditional bush roller chain.

Despite this type of chain drive tracing its roots all the way back to Leonardo da Vinci, they actually offer many advantages over the fancy carbon-fiber-reinforced polyurethane belt. Although with the Pinion gearbox the inability to use a derailleur gearing system is no big deal, [Tristan] found that the ‘zero maintenance’ part of the belt was not true for less hospitable roads

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Quieting Noisy Resistors

[Hans Rosenberg] has a new video talking about a nasty side effect of using resistors: noise. If you watch the video below, you’ll learn that there are two sources of resistor noise: Johnson noise, which doesn’t depend on the construction of the resistor, and 1/f noise, which does vary depending on the material and construction of the resistor.

In simple terms, some resistors use materials that cause electron flow to take different paths through the resistor. That means that different parts of the signal experience slightly different resistance values. In simple applications, it won’t matter much, but in places where noise is an important factor, the 1/f or excess noise contributes more  to errors than the Johnson noise at low frequencies.

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How The Intel 8087 FPU Knows Which Instructions To Execute

An interesting detail about the Intel 8087 floating point processor (FPU) is that it’s a co-processor that shares a bus with the 8086 or 8088 CPU and system memory, which means that somehow both the CPU and FPU need to know which instructions are intended for the FPU. Key to this are eight so-called ESCAPE opcodes that are assigned to the co-processor, as explained in a recent article by [Ken Shirriff].

The 8087 thus waits to see whether it sees these opcodes, but since it doesn’t have access to the CPU’s registers, sharing data has to occur via system memory. The address for this is calculated by the CPU and read from by the CPU, with this address registered by the FPU and stores for later use in its BIU register. From there the instruction can be fully decoded and executed.

This decoding is mostly done by the microcode engine, with conditional instructions like cos featuring circuitry that sprawls all over the IC. Explained in the article is how the microcode engine even knows how to begin this decoding process, considering the complexity of these instructions. The biggest limitation at the time was that even a 2 kB ROM was already quite large, which resulted in the 8087 using only 22 microcode entry points, using a combination of logic gates and PLAs to fully implement the entire ROM.

Only some instructions are directly implemented in hardware at the bus interface (BIU), which means that a lot depends on this microcode engine and the ROM for things to work half-way efficiently. This need to solve problems like e.g. fetching constants resulted in a similarly complex-but-transistor-saving approach for such cases.

Even if the 8087 architecture is convoluted and the ISA not well-regarded today, you absolutely have to respect the sheer engineering skills and out-of-the-box thinking of the 8087 project’s engineers.